The prior art is replete with a variety of compositions directed toward the effective killing of bacterial spores. Among the most important developments in this area are the compositions disclosed in U.S. Pat. No. 3,016,328 to Pepper et al and U.S. Pat. No. 3,282,775 to Stonehill. In the former patent saturated dialdehydes provide sporicidal activity and the pH of the composition is controlled so that it is maintained in excess of 7.4 by including an alkalinizing agent. The sporicidal composition disclosed in the latter patent to Stonehill is also characterized as containing a saturated dialdehyde, including cationic surface active agents. In the Stonehill patent; it is expressly stated that anionic and/or nonionic detergents do not increase the sporicidal activity of the compositions.
While the patent to Pepper et al limits the pH of the sporicidal composition to a minimum in excess of at least 7.4, the Stonehill patent discloses no such limitation as the compositions disclosed therein are stated to be effective over a wide pH range of 4.0-9.0.
Each of the sporicidal compositions disclosed in the above-identified patents claim very fast sporicidal action of about 3 hours or less. However, close examination of the conditions upon which such fast kill claims were determined reveals that the "kills" were obtained against readily susceptible bacterial spores and that neither patent discloses any sporicidal activity results for bacterial spores on silk sutures, which carrier is specified as being required by the AOAC test procedure. Futhermore, it is well known that resistance of bacterial spores to chemical sterilizing agents is lowest in free suspension, intermediate on porcelain rings and most resistant on silk sutures. Recently, the claims for sporicidal compositions marketed by the common assignee of the above-noted patents had to be revised in their registration with the USDA from a contact kill time of 3 hours upward to 10 hours.
Independent analyses of the sporicidal compositions disclosed in U.S. Pat. No. 3,016,328 to Pepper et al revealed that the 10 hour contact kill time was readily obtainable when using a fresh solution, but that the efficacy of the compositions markedly decreased upon standing for prolonged periods of up to about 2 weeks. Further, this reduction in effectiveness was found to be attributable to the diminution of glutaraldehyde, which lost a total of about 25% of its value by the end of a 2 week period.
It can be seen, therefore, that these two principal disclosures relating to sporicidal compositions, under the limited test conditions set forth therein may not, in reality, exhibit the effectiveness implied for them with respect to passing the complete AOAC test. Furthermore, the effectiveness of the disclosed compositions are based upon those bacterial spores and/or carriers which are known to favor relatively easy "kills.